1. Field of the Invention
This invention pertains to stents for use in intraluminal applications. More particularly, this invention pertains to a stent with enhanced friction on a delivery catheter.
2. Description of the Prior Art
Stents are widely used for numerous applications where the stent is placed in the lumen of a patient and expanded. Such stents may be used in coronary or other vasculature, as well as other body lumens.
Commonly, stents are cylindrical members. The stents expand from reduced diameters to enlarged diameters. Frequently, such stents are placed on a balloon catheter with the stent in the reduced-diameter state. So placed, the stent is advanced on the catheter to a placement site. At the site, the balloon is inflated to expand the stent to the enlarged diameter. The balloon is deflated and removed, leaving the enlarged diameter stent in place. So used, such stents are used to expand occluded sites within a patient""s vasculature or other lumen.
Examples of prior art stents are numerous. For example, U.S. Pat. No. 5,449,373 to Pinchasik et al. teaches a stent with at least two rigid segments joined by a flexible connector. U.S. Pat. No. 5,695,516 to Fischell teaches a stent with a cell having a butterfly shape when the stent is in a reduced-diameter state. Upon expansion of the stent, the cell assumes a hexagonal shape.
To deliver a stent, the stent in a reduced diameter shape is placed surrounding a deflated tip of a balloon catheter. The catheter and stent are simultaneously advanced through a sheath to a deployment site in a body lumen. At the site, the balloon is inflated to expand the stent. Following such expansion, the balloon is deflated. The catheter is withdrawn leaving the expanded stent in place.
In order to prevent the presence of sharp corners and burrs which might otherwise damage a balloon, stents are highly polished to a mirror finish. Unfortunately, a highly polished stent can slip off a balloon tip catheter. Also, when a balloon is inflated, the axially spaced ends of the balloon tend to inflate faster than the center of the balloon. This can result in a concave cross-section (when viewed from the side) in the balloon and stent at a point in time prior to full expansion of the stent. During this period, ends of the stent may slide toward one another on the balloon toward the center of the balloon resulting in an undesirable compression of the length of the stent.
According to a preferred embodiment of the present invention, a stent for placement in a body lumen is fabricated by forming a tube having an un-deployed diameter sized for the tube to be placed on a deployment balloon and advanced through a body lumen to a deployment site. The tube is expandable upon inflation of the balloon to an enlarged diameter sized for the tube to be retained within the lumen at the site upon deflation and withdrawal of the balloon. The tube has a stent axis extending between first and second axial ends of the tube. The tube has an exterior surface and an interior surface. The tube is polished to polish the exterior surface to a smooth surface finish and with at least a portion of the interior surface having a rough surface finish rougher than the surface finish of the exterior surface.